It is well known among transmission experts that in order to optimize drive strategies and gear change operations of automated manual transmissions, the information of the current motor or gear input torque is needed. In practice, the current torque is measured by taking the crankshaft or gear input shaft rotational speeds as well as the accelerator pedal position into consideration, which allow the present torque on the crankshaft and/or on the gear input shaft to be determined with the help of a characteristic torque curve that is stored in an evaluation and control unit.
In case of retarders, i.e., wear free service brakes of the vehicle, according to the state of the art, their braking torque is determined as a function of the braking pressure and a characteristic curve which is also recorded in a control and regulating unit. Good regulation of the braking effect of retarders, however, is not quite possible based on such a measurement of the braking effect.
Starting from this state of the art, the object of the invention is to develop a method and a device with the help of which the change in input torque of a transmission or the braking torque on a retarder can be determined easily and quickly.